Spectral densities from the lattice

Abstract

We discuss a method to extract the Källén-Lehmann spectral density of a particle (be it elementary or bound state) propagator by means of 4d lattice data. We employ a linear regularization strategy, commonly known as the Tikhonov method with Morozov discrepancy principle. An important virtue over the popular maximum entropy method is the possibility to also probe unphysical spectral densities, as, for example, of a confined gluon. We apply our proposal to the SU(3) glue sector.

Comments: 7 pages, 9 figures, talk given at the 31st International Symposium on Lattice Field Theory (LATTICE 2013), July 29-August 3 2013, Mainz, Germany